Solar Eclipse!

A Special Day

The solar eclipse on August 21st was only partial at my home in Williamsburg. From my back yard, at maximum eclipse, 88 percent of the solar diameter was blocked, and 85.6 percent of the solar area was covered. Years and months before the eclipse I debated the merits of traveling somewhere to be in the path of totality. If I traveled, I wouldn't take my solar telescope. I would experience totality, but probably not get any worthwhile images. If I stayed home, I could try using my telescope to get hydrogen-alpha images of the lunar limb covering solar features. In the end, I decided to stay home and see how my telescopic imaging system would perform.

Several weather forecasts predicted nearly clear skies for August 21st. I set up my equipment hours before noon to be well prepared for the afternoon eclipse. I also wanted to get images of sunspots on the solar disc before the Moon came on the scene. Fortunately, a major sunspot group was located near center on the solar disc along with another smaller group near the western limb. These provided nice background features for the Moon's limb to cover during the eclipse. The Sun had often been nearly featureless recently, so the appearance of these sunspots was an unexpected bonus.

As often happens, predictions of cloud coverage were inaccurate. Near 10:00 am EDT several drifting clouds were present, but not enough to make imaging impossible. At 10:14 I captured the following image of large sunspot group 2671 near center on the solar disc. Lots of complex structure is visible. (Click on any image below for larger views.)

Clouds soon increased. It became harder to find clear gaps large enough to get an unobstructed view. I had to wait 35 minutes before getting one chance to capture the other sunspot, 2672, seen below.

At this point things looked bleak for viewing the afternoon eclipse! I shut down my equipment and had some breakfast.

Two hours later my telescope and computer were powered up and ready to go for the beginning of the eclipse. Clouds with gaps drifted across the sky. The Sun crossed the meridian at 1:10, so I waited until then before locking the telescope on the Sun. (This avoided an inconvenient meridian flip required by my German equatorial mount.) The first appearance of the Moon's black disc on the Sun's edge was scheduled at 1:20. I wasn't quick enough to capture this event. My first image at 1:26 was unremarkable, but 18 minutes later, at 1:44, the Moon's edge appeared just to the right of (west of) the largest umbra in sunspot group 2671 as shown below.

Seven minutes later the lunar limb (moving right to left, or, eastward) had passed the large umbra and moved over erupting white energetic emissions shown in  the next picture.

By comparing the two previous images you can see how much the Moon had moved in about 7 minutes. The Moon's eastward motion relative to the Sun was easily visible in real time on my laptop screen as smaller solar features were continuously eclipsed. This was a rare opportunity to witness lunar orbital motion with only a few seconds of observation!

I wondered if lunar motion would smear out detail along the lunar limb. This turned out to be true. Most of my video clips were limited to 400 frames which took about 11 seconds to record. The image processing software I use to produce still images from the video clips did a good job with relatively steady solar features, but detail along the lunar limb was not resolved. The software produced a thin bright border along the moving lunar limb.

I thought an image of the lunar limb crossing a sunspot umbra would be interesting. Unfortunately, a big cloud blocked the Sun at the moment this crossing occurred. So I have only before and after crossing pictures above. By the time clouds thinned somewhat, the entire sunspot group had been covered, and the lunar limb was moving over bland surface features.

Two modest prominences were present on eclipse day. Another interesting image, I thought, would be the lunar edge crossing a prominence on the Sun's limb. The next image shows one such event where you can see the Moon's limb extending beyond the solar disc.

My daughter's family, one of her friends, and some of our neighbors also viewed the eclipse with me. I was so happy to share my astronomical enthusiasm for a couple hours. In the next image my daughter is looking through eclipse glasses while I'm watching a magnified telescopic hydrogen-alpha view on a laptop screen. The laptop is shaded by a cardboard box, and I'm shaded by an effective clamp-on umbrella recently purchased.

My little granddaughter, Annabelle, was happy to play for a while on her blanket. You can see the partly clouded sky in the background.

My other granddaughter, Sophie, pronounced eclipse views, "Cool!". She shared a view of my laptop screen and also saw the entire solar disc in hydrogen-alpha through my telescope. Not many 7-year-olds can claim the same experience.

Of course, we had to try the old "colander" trick showing multiple crescent images of the nearly maximum eclipsed Sun. I had never noticed the appropriate star-shaped hole pattern before.

We had two pairs of solar filtered binoculars, eclipse glasses, the telescope, and various pinhole devices. My son-in-law had fun looking through all the various optical instruments.

Sophie and her close friend, Portia, shared a view through filtered 100X25 binoculars.

Eclipse maximum happened at about 2:46. The sky became noticeably dimmer for a short while near this time. Soon after maximum clouds began to thin and seeing became much better as the atmosphere steadied. At 3:00 I captured the following view of the largest solar prominence being uncovered by the receding Moon. (The Moon is moving from right to left here.)

Ten minutes later I could see large sunspot group 2671 being uncovered as the Moon continued moving eastward across the Sun.

Fourteen minutes later all of sunspot group 2671 was uncovered.

Just before 4:00 sunspot 2672 was completely uncovered.

The Moon's "bite" on the Sun was rapidly diminishing. At 4:04:40, just 39 seconds before the predicted end of eclipse at my location, I captured this final view of the lunar limb leaving the Sun.

After the eclipse I felt exhilarated, but also completely exhausted. Heat drains my energy. The temperature had been in the low 90's since noon. My shirt was soaked through, especially after hauling all the equipment inside. I could barely keep my eyes open for the rest of the day, including during a dinner to celebrate C's birthday, which, coincidentally, also fell on eclipse day!

I might be able to use some of the many images not included here to create an animation showing the Moon covering the large sunspot group. Perhaps I'll include that in my next post.
  

Double Feature!

Prominence and Sunspot

An enormous prominence was suspended above the Sun's eastern limb on July 8th. Nearby was a growing active sunspot. The sky, rarely clear during July, was cloudless, so I seized the opportunity to image these dramatic features. Only brief puffs of gentle breeze gave any relief from the heat with temperature at 85 degrees while I worked.

The first image below is a 14-panel mosaic made with a 5X Barlow lens. It shows the Sun's eastern side with sunspot 2665 and several prominences along the limb. (Click on the image for a more detailed view.)

The next image is a closer view of the largest prominence and sunspot 2665. White energetic emissions erupt in the middle of the sunspot group. The giant prominence is several Earth diameters high.

It's hard to work comfortably in humid July heat. My shirt was soaked with perspiration after only 35 minutes. More than three months have passed since the last time I used my solar telescope. It may be months again until conditions are right for another solar imaging session.

Double Shadow Transit on Jupiter

Three Moons and the Red Spot!

Orbiting Jovian moons sometimes pass in front of Jupiter and sometimes behind. When they pass in front, it's possible for their shadows to fall on Jupiter. There have been several recent opportunities to see two of these shadows on Jupiter at once! Unfortunately, it was cloudy at my location every time. Finally, on June 3rd, conditions were good enough to try observing this interesting phenomenon. Scattered clouds filled the sky as I set up my telescope. As darkness fell, clouds diminished leaving a slightly hazy sky. With no wind, and temperature at 74 degrees, it was very comfortable working outside at the telescope. Jupiter was about 1.5 degrees below the 75 percent illuminated Moon, forming an attractive pair.

I captured the image below at 10:15pm EDT, just after the first shadow entered Jupiter's disc. Two moons visible to the right of Jupiter are Ganymede and Callisto, with Ganymede above Callisto. Another moon, icy Europa, was left of Jupiter, but too dim to show in any images I took. The final Galilean moon, volcanic Io, cast the black shadow seen below. Io itself was located directly in front of Jupiter's disc to the right of the shadow. Consequently, Io is hard to distinguish from bright background planetary features in this image.

At 10:21pm EDT Ganymede's shadow can be seen making a small, black entrance notch in the upper left of Jupiter's disc.

Ten minutes later, at 10:31pm EDT, Ganymede's shadow was still entering the disc. Notice the small, pale red spot nearly centered in the bottom white zone.

In another 10 minutes, at 10:41pm EDT, Ganymede's shadow had fully entered the Jovian disc. An observer sitting within one of these shadows on Jupiter would see the Sun eclipsed by a Jovian moon!

In the next image, taken 30 minutes later at 11:11pm EDT, you can finally see the tiny white disc of Io about to exit the dark belt on Jupiter's right edge.

At 11:21pm EDT, Io had completely exited the Jovian disc and was now clearly visible on the right against a black sky. Jupiter's great Red Spot was also rotating into view on the lower left edge.

My hopes of following shadows entirely across the disc were dashed by increasing haziness over the whole sky. Jupiter was also getting closer to the horizon. Soon, a bright 22-degree circle formed around the nearby Moon. I had to increase my exposure times as Jupiter began to fade behind the thickening haze. My last image, at 12:01am EDT, June 4th, shows the Red Spot, two shadows, and three moons! Wow!

I made a time lapse animated GIF using 14 images recorded between 9:41pm EDT and midnight. This little video compresses 2 hours and 20 minutes of Jovian motion into about 2 seconds. Jupiter rotates, moons orbit, and shadows transit the disc!

By the time I got to bed after 1:00am, I was exhausted. My 52-mile bike ride the next morning completely wiped me out. But it was worth the effort to record this beautiful celestial event! 

Jupiter

Red Spot!

More than a year has gone by since my last attempt to image Jupiter. It was time to try again in nearly perfect conditions on the evening of May 15th. The sky was completely clear with very little wind and low humidity as the temperature dropped from pleasant middle 60's to slightly chilly low 50's during my time outside.

I lost some telescope operating efficiency while my Stellarvue 130mm refractor sat idle for so many months. Consequently, I made several blunders during set up. The most serious mistake was forgetting to sufficiently tighten screws holding the telescope in the mount. When the mount performed its initial homing slew the telescope began sliding down out of the mount and was well on its way to crashing into the concrete observing pad below. Fortunately, I happened to be standing next to the mount and desperately caught the sliding telescope in my arms at the last minute before any damage was done. Yikes! How could I be so dumb?

I also used a new laptop for this imaging session, so there were several delays getting software to communicate with the mount and the camera. Finally, since I stupidly forgot to line up the finder scope with the main telescope, it took way too long to get Jupiter centered in the eyepiece after the mount initially failed to place Jupiter in the field of view. In spite of these problems Jupiter eventually appeared on my laptop screen and I began recording images. The initial view looked like the first image below, recorded at 10:23 pm EDT with a 3X Barlow lens.

Three Galilean moons are visible to the right of Jupiter. They are, from left to right, Io, Europa, and Ganymede. The fourth moon, Callisto, was out of the field of view far off to the right. At first I didn't realize that Jupiter's Red Spot was located on the lower left edge of Jupiter, ready to rotate into view over the next hour. Can you see the hint of the Red Spot on the left edge of the lowest white band?

Just 29 minutes later, at 10:52 pm EDT, the Red Spot had become more visible as you can see in the next image.

The moons hardly changed position during the 29 minutes between the first two images. The Red Spot, however, was coming into better view. The next image was captured at 11:18 pm EDT, 26 minutes after the previous image.

I switched to a 5X Barlow for the next image, captured 17 minutes after the previous image at 11:35 pm EDT. The 5X Barlow gives too much magnification for my telescope/camera combination, so I have to reduce the image size by half to display a pleasing amount of detail.

Finally, I switched to a 2X Barlow lens and took this last image after midnight at 12:08 am EDT on May 16th. Another 33 minutes had passed since the previous image.

While I captured the images above over a span of one hour and 45 minutes the Red Spot rotated from the edge of Jupiter around to nearly the central meridian. From the image sequence you can see it would take more than two hours for the Red Spot to rotate halfway across the face of Jupiter. The exact time is 2 hours and 29 minutes, making the Red Spot's transit time across Jupiter's face 4 hours and 58 minutes. (The sidereal rotation period of Jupiter is about 9 hours 55 minutes. Half this period is 4 hours 58 minutes.) 

Because the Red Spot isn't obviously visible near the very edges of Jupiter, visual observers have less than four hours to see it cross the Earth-facing disc of Jupiter. During these four hours good observing conditions are required. Jupiter needs to be above the horizon on a clear night. No wonder I've rarely seen the Red Spot.

Rock Show

Minerals, Meteorites, Fossils, Gems!

I recently visited the NY/NJ Mineral and Gem Exposition in Edison, NJ. The long, unpleasant drive from Virginia on Interstate 95 wasn't much fun, but when I first entered the vast exposition hall, I immediately knew my journey was worthwhile! Spread before me was the equivalent of hundreds of rock shops all in one place. It took more than one day to see all the displays and shop for additions to my modest collection of curiosities.

Many display cases were simply beautiful. For example, look at this orderly array of colorful crystals.

Some dealers had elaborate glass display cases.

I wanted to purchase one of the beautiful blue specimens of benitoite, pictured below, but they were incredibly expensive. The benitoite specimen in the upper left of the next image was priced at about $7,000!

Next to the benitoite was a meter-high array of blue fluorite crystals.

High intensity lights, strategically placed, increased the attractiveness of many displays like this next one.

During a visit to Denver years ago I saw red rhodochrosite crystals and thought they would be a great addition to my collection. I hoped to buy a rhodochrosite specimen, but, as you can see below, they were surprisingly expensive, even for a small specimen. I really liked the large $775 specimen with the colorful pyrite foreground.

A few vendors were selling meteorites like the ones in this display case.

I'm particularly fond of pallasite meteorites whose cross-sectional slices look like stained glass windows. Several expensive slices were displayed in the case shown in the next image. Meteorites are usually sold by weight. The pallasite slices were going for something like $20/gram! Since the slices are mostly heavy nickel and iron, there are quite a few grams involved! The slice in the upper left was about $2,600! (Unfortunately, there was no way to get a picture without white reflections from overhead lights.)

Many exquisite fossils were also on sale.

Not sure where I would display this enormous 30,000 year-old cave bear fossil even if I could afford its $29,500 price!

By the end of my second day at the expo I was completely exhausted from walking around peering at specimens. As I was about to leave I saw a sign for an ultraviolet light display, so I took one final detour from the main floor to look at displays of fluorescent minerals under ultraviolet light. I'm glad I made the effort because the exhibit was amazing and beautiful as you can see in the next two images.

I ended up buying an ultraviolet flashlight and a couple of phosphorescent minerals to show my granddaughter. I left the expo very satisfied with the whole experience.

At this point it was way past lunch time, and I was starving in addition to being exhausted. I decided to eat at nearby Harold's New York Deli, an over-the-top authentic Jewish deli, where truly ENORMOUS portions are served. For example, the sandwiches are about a foot high, packed with so much meat it's nearly impossible for one person to eat an entire sandwich at one sitting. (The patrons deconstruct towering sandwiches into manageable sizes and, either share the smaller sandwiches with companions, or take the remains home to eat for a week.) The smallest menu item I could find was the thick, foot-long hot dog with sauerkraut seen below. I was able to finish it, but it was quite a salty overload to my system. It cured my hot dog craving for the foreseeable future. I enjoyed the NJ atmosphere of the place with NJ/NY accents all around.

Below are pictures of some of the minerals I bought. First is brilliant green dioptase from Kazakhstan. This specimen was surprisingly beautiful under short wave ultraviolet light. The white matrix fluoresced bright red!

Next is lazurite and pyrite from Afghanistan. The blue and gold colors are dazzling under bright light.

This strange round ball is prehnite sitting on epidote from Mali.

Multiple cubic pyrite crystals are always interesting. These are from Spain.

Finally, below are three images of my favorite purchase, a polished slice of the Seymchan pallasite meteorite discovered in 1967 in Magadan, Russia. This bit of extraterrestrial material was once located near a boundary between the core and mantle of a differentiated asteroid. It contains silvery crystallized iron and nickel, characteristic of the core, and pieces of the silicate olivine, characteristic of the mantle. Some unknown ancient catastrophe blasted the asteroid to bits. One of these bits ended up in Russia! Now it sits in my living room. The first image, made with a flash, shows fascinating structure resembling a stained glass window.

The next image, made without flash, emphasizes light passing through the partially transparent olivine.

This last image best shows the unique silvery iron/nickel crystallization structure known as the Widmanstatten pattern.

I'm so glad I made the effort to attend this expo. 

 

Sun Wakes Up

Two Significant Sunspots

Recent months of sunspot drought temporarily ended on April 2nd when two good-sized sunspots were visible on a cool, cloudless day. A northerly breeze accompanied 51-degree temperature as I set up my solar telescope to begin observing before noon. Seeing was not particularly good, but blue skies and sunshine were very welcome.

My attempt to construct a whole disc mosaic failed because I was careless when capturing constituent panels. But the smaller successful 9-panel mosaic below shows almost all major solar features present. Complex sunspot group 2645 is on the lower left. Sunspot group 2644 is near the right limb. A few prominences sit on the western limb.

Seeing conditions improved for a while as morning hours passed. The next image is a close view of sunspot group 2645 made by stacking the best 100 frames from a 3,000-frame video. Notice the fine detail present in the dark sunspot umbras. This sunspot group deformed surrounding spicules making a pattern similar to iron filings sprinkled near a bar magnet. White energetic eruptions sit between outlying umbras. (Click on the images for a larger view.)

Sunspot group 2644 was churning with activity near the western limb. I recorded 21 minutes of the action by capturing one 500-frame video clip every 60 seconds. Each video clip yields a still image which becomes one movie frame. The repeating movie below runs at 10 frames per second, so it compresses 21 minutes of solar action into about 2 seconds. Movies like this always make me wish I had recorded longer. Unfortunately, I had to stop too soon.

The Sun may soon go back to sleep, so I'm glad I was able to observe this temporary burst of activity.